tance, decrease in mortality is an end in itself; decrease or increase in natality is usually a means to many social ends, one of which is reduction of mortality. Nations and different groups in a given society will seek different social objectives and different specific levels of natality control at any given time. Japan has sought a natality level which would achieve a stable population for its crowded islands at the same time that India seeks a natality level which will increase the rate of social and economic development. Chile seeks a better means of natality control than illegal abortion, and the United States seeks opportunity for the poor to prevent unwanted births equal to the opportunity already available to the rest of the population. Second, the social objectives of natality control usually require a longer time interval for attainment than the social objectives of mortality and morbidity control. The effects of a prevented birth on educational services follows 5 to 20 years after the event, on employment 15 to 60 years later, on health and health services differentially over the life span (Figure 2). Although in time the effects of a prevented infant death are not much different, most health programs affect all age groups; for example, the effect of reduced disability from malaria on employment is relatively rapid. BIRTH 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 ^^ YEARS AFTER BIRTH - AGE Figure 2. Time relationships between a birth and future service requirements. The Impact of Health Services It is beyond the scope of this paper to deal adequately with the relationships between health services and mortality (and morbidity) (3, 4). It is assumed that health services do contribute significantly to lowering mortality (and morbidity), that efforts of health services to control mortality (and morbidity) will continue at present or higher levels, and that mortality (and morbidity) levels of LDC's will continue to decrease toward the levels of m^m A0ira\nnarl ,->,-vi,n+i-;ģe /1UTV"cAloping Countries." Report No. EC-157. Washington, D.C.: Inter-natl. Bank for Reconstruction and Development, December 20, 1967.